Technical Abstract:
The introduction and subsequent invasion of cheatgrass (Bromus tectorum) onto millions of hectares of rangelands throughout the Intermountain West has had devastating effects on a variety of plant communities by promoting a fine textured, early maturing fuel that increases the chance, rate and spread of wildfires. In July of 2006, a wildfire burned a Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) community in northeastern Nevada. We implemented an experiment to test the importance of 1) timing of restoration/revegetation efforts, 2) mechanical weed control, and 3) plant species initial sprouting, establishment and cheatgrass suppression potential. We established sixty 20m x 60m plots. Thirty of the plots were seeded to various species in the fall of 2006, while the other 30 plots were seeded the fall of 2007. Fifteen plots of each year were also disced and fallowed to test mechanical cheatgrass control. Cheatgrass seed banks were also measured and recorded. The seeded treatments were a) ‘Hycrest’ crested wheatgrass (Agropyron cristatum), b) Sherman big bluegrass (Poa ampla), c) Bottlebrush squirreltail (Elymus elymoides), and d) the mixture of these species with the addition of Indian ricegrass (Achnatherum hymenoides), Wyoming big sagebrush, ‘Immigrant’ forage kochia (Kochia prostrata) and “Ladak’ alfalfa (Medicago sativa). There were no significant differences in plant establishment in disced versus undisced plots. 2006 seeded treatments a) crested wheatgrass and d) mix, were the most successful at establishing, 9.3/m² and 9.7/m² compared to seeded treatment b) Sherman big bluegrass and c) squirreltail, .75/m² and 1.1/m², respectfully. The discing of the soil at this site resulted in a significant decrease in cheatgrass germination from 300.5/m² down to 88.6/m² in the 2006 plots and from 382.1/m² down to 182.2/m² in the 2007 plots. The above ground cheatgrass densities however, were not significantly different on the seedling year for the 2006 plots, disced = 7.98/m² undisced = 8.51/m², but were significantly different for the 2007 plots yielded 22.8/m² and 38.5/m² for the disced and undisced plots, respectfully. Established (two year old plants) seeded treatment a) crested wheatgrass and d) mix significantly reduced cheatgrass densities, 6.2/m² and 7.5/m² compared to 126.1/m² for big bluegrass and 175.6/m² for squirreltail. Added cheatgrass suppression was also recorded for those plots seeded the first fall versus the second fall following the wildfire.